It wasn’t for a lack of tips from the public that the biggest robbery in Vermont history remains unsolved to this day.

Eleven years after a lone gunman made off with $1.9 million from the Berkshire Armored Car Co. office in Rutland, a former city detective long assigned to the case said he still fielded calls about the robbery as late as 2009.

“I interviewed a lot of people,” said Michael Notte, who left the city police department for a job with Vermont State Police in 2011. “A lot were based on people suspecting someone they knew who had made a major purchase, like buying a car, with cash. They assumed it had to be tied to the Berkshire money.”

While many of the leads were long shots, Notte said he chased them down on excursions that sometimes took him to Connecticut and New York and often involved the use of a lie detector.

But all of the tips and interviews lacked the one thing investigators needed, he said.

“I can tell you a lot of those all come down to proving your case and evidence,” he said Thursday, on the anniversary of the infamous heist.

Asked if a prime suspect ever emerged from the case — or if he had any personal theories about who carried out the crime, Notte simply shook his head.

“It would be unfair of me to say I know anything about who it could be,” he said.

While the FBI has closed its investigation, the case hasn’t been officially closed in Rutland. But it was not assigned to another detective after Notte left the department, according to city Police Detective Sgt. Kevin Stevens.

“What are you going to do? You can’t have it sitting on someone’s desk forever,” Stevens said.

The FBI made a similar decision after investigating the case for about a decade.

Paul Holstein, the FBI media coordinator in Albany, N.Y., said Thursday that the statutes of limitations on all of the possible charges that could be brought in the case, along with the need to assign agents to other cases, led the agency to put the Berkshire investigation under a case-closed status.

“The bottom line is we’re trying to ensure we use our resources effectively to perform prevention and support functions in terrorist cases and other situations involving threats to the public’s safety,” Holstein said. “When we have an investigation open we’re actively investigating it. We need to look over time at how prudent it is to keep an investigation open and resources devoted to it.”

That said, Holstein said the FBI would look into any future leads on the robbery and present a case to the U.S. attorney in Vermont if evidence could be found to support a charge that hadn’t lapsed under the statute of limitations.

In Burlington, U.S. Attorney Tristram Coffin said Thursday that the possibility remained for bringing charges related to spending or transporting money stolen during the heist.

“If we can get evidence in the future, we’d be happy to prosecute it,” he said.

But prosecuting an 11-year-old case can be a challenge. Statutes of limitations apply to criminal offenses because, as years pass, the evidence in cases gets harder to prove.

The Howe Center site once occupied by the armored car company is a car repair shop these days and the vault that housed the hundreds of pounds worth of bills stolen in the heist is sitting in a Pawlet field, according to Joseph Giancola.

Giancola has the unusual distinction of being the man who owns both the Howe Center and the 10,000-pound stainless steel vault.

After Berkshire left Rutland in the middle of the last decade, Giancola said he gave the vault to his friend, Tony Keough, to store dynamite in at Switch Road Slate in Pawlet.

Keough used to be the sole owner of the slate company but in recent years, ownership has passed to K&G Limited. The “K” stands for Keough, the “G” for Giancola.

“Those are pieces of Rutland folklore,” Giancola said Thursday, referring to both the Howe Center and the safe which he said is standing open and empty in a field by the slate mill.

Back when the robbery took place, Giancola did his part by turning over video cameras he had recently installed in a car wash near the armored car company’s offices.

He heard plenty of rumors, too, about suspected culprits but he said he never directed his own suspicions at anyone in particular.

“It’s a D.B. Cooper story,” he said, referring to the name given to an unknown aerial bandit who robbed a 747 in midair before parachuting to an unknown fate over Oregon in 1971.

From an investigator’s perspective, the mystery is no less perplexing.

While the execution of the robbery appeared no more complex than some convenience store stick-ups, the lack of evidence and lengthy list of potential suspects has hindered the investigation.

The facts laid out by police in the past are that a lone man clad in a dark jacket and ski mask confronted a guard arriving for work.

The suspect, armed with a revolver, forced his way inside and took a pistol from another guard already in the building. He handcuffed and tied both guards, hauled off the bags of money from the vault and made his getaway in a dark van.

Rumors in the city have long contended that the simplicity of the robbery belied some degree of inside information possessed by the robber. A common rumor holds that the robber must have had help from a guard or other employee at the armored car company.

But Notte said the evidence he gathered indicated that the gunman didn’t need any inside help to come up with a plan for robbing the office.

While the office didn’t begin holding such large amounts of cash in its vault until roughly six months before the robbery took place, the former detective said a lack of security at the offices made the large infusions of money and the company’s daily operations easy to see.

“It wasn’t uncommon for the bay doors to be open,” he said. “Anyone could have been watching and learning. It could literally be anyone.”